This invention relates to latches for joining two members, which latches exert a pulling force from one member to the other for bringing the two members together during the latch closing operation. The extended release latch of the present invention is suitable for various latching installations, and is particularly adapted for use with aircraft engine cowls.
Aircraft engine cowls are secured by latches for ease of access for maintenance and safety checks. The newer engine cowls are being constructed with a greater number of compressible seals than in the past. As a result, the cowlings not only require more force to close but this force is encountered when the cowlings are spaced further apart.
The new generation engine cowls are larger and have more effective seals along the cowlings. The net effect of more seals and larger seals is to offer more resistance to the cowl closing. In past installations, the weight of the cowls has been sufficient to compress the seals and bring the two portions within the engagement range of the conventional hook latches.
Compression seals in use today are in the order of two and one-half inches in size, which means initial engagement of the hook of the latch with the keeper of the latch must occur with a two and one-half inch gap between the two members being joined. The latch must then function to decrease this gap to zero for compressing the seals and applying a preload to the cowling.
In the present day installations utilizing conventional latches, some additional help is required in initially engaging the latch hook on the keeper. In one approach, several workers are utilized to push the cowlings together, compressing the seals, until the first latch is able to be engaged. In another arrangement, an additional tool, sometimes referred to a come-along, is utilized to initially reduced the gap at the members being joined. Large handle forces are then required to further compress the seals and close the latch.
One previous attempt to solve this problem, as on the Concorde, was to have a single large latch which could be used to engage the two cowl members and to pull them into a proximity whereby smaller structural latches could then be engaged and closed. The disadvantage to this method is that the large latch then becomes unloaded and is carried as a weight penality.
Accordingly, it is an object of the present invention to provide a new and improved latch which can be utilized with newer engine cowls to enable closure with operation by a single worker, while also functioning as a load carrying latch in flight. A latch of this nature is sometimes referred to as an extended reach latch or extended take up latch.
Other objects, advantages, features and results will more fully appear in the course of the following description.